• 作者： 盧天惠
• 作者服務機構： Dept. of Physics, National Tsinghua Univ., R.O.C.
• 中文摘要： The cell dimensions are a=b=131.2, c=198.5.ANG., and.alpha.=.beta.=90.degree.,.gamma.=120.degree. for both the wild and the mutant types of aspartate transcarbamoylase ( ATCase) crystallized at pH=7.0. The space group is R32. Although the mutant and wild forms of ATCase show large differences in enzyme activity and chemical reactivity, yet they are isomorphous in structure.
  One asymmetric unit of ATCase contains a catalytic subunit, molecular weight 34,000 daltons, and a regulatory subunit, molecular weight 17,000. There are 310 amino acids in the catalytic subunit and 162 amino acids plus zinc in the regulatory subunit. The whole ATCase is a hexamer and consists of six molecules of catalytic and regulatory subunits. The primary structure study of this enzyme shows that the mutant form has a single substitution of aspartic acid in place of glycine at position 128 in the amino acid sequence of the catalytic chains. In most part of the sequence, the regulatory and catalytic chains of mutant and wild forms of ATCase are in similar conformations.
  (2Fo-Fc) syntheses displayed with computer graphics using the FRODO program, were applied to the reflection data from both mutant and wild types. A stereoview of certain regions displayed on PS300 graphics shows significant differences between the wild and mutant types of ATCase.
• 英文摘要： --
• 中文關鍵字： X-Ray Analysis; Aspartate Carbamoyltransferase; Native Atcase; Mutant Atcase; E. Coli
• 英文關鍵字： X光分析；天冬酸氨基甲醯轉化；原種天冬酸氨基甲醯轉化；突變天冬酸氨基甲醯轉化；大腸菌